1. Field of the Invention
The invention relates to a bioreactor with a vessel having at least one gas dissipation duct for gas discharge, the orifice of the gas dissipation duct being connected to a sterile filter and to a condenser arranged between them and having condensation surfaces. The invention relates, furthermore, to a condenser for a bioreactor.
2. Description of the Related Art
In the gassing of a bioreactor, the air supplied absorbs moisture while the medium flows through. The same effect occurs in biotechnological processes in which gases are formed as metabolic products of microorganisms and are dissipated out of the bioreactor. Using an outflow condenser in the outflow system makes it possible to prevent the exhaust air from carrying some of the medium out with it. Warm, moist exhaust air is cooled down by the condenser to such an extent that the medium contained in the exhaust air flows as condensate back into the boiler.
U.S. Pat. No. 5,443,985 A discloses a bioreactor with a vessel composed of a borosilicate glass or of stainless steel, which at its vertically upper end has a gas dissipation duct for gas discharge. In this case, the orifice of the gas dissipation duct is closed by means of a sterile filter. A water-cooled condenser is arranged between the vessel and the sterile filter, parts of the inner surfaces of the gas dissipation duct forming the condensation surfaces required in the condenser. The vessel of the known bioreactor is supplied at its vertically lower end with gas via a gas routing duct.
In the known bioreactor, the inner wall surrounding the gas dissipation duct forms the condensation surface of the condenser. The condenser has a double wall, through which the cooling water is led.
The disadvantage, here, is that, in the case of a largely laminar flow, a relative long gas dissipation duct is required in order to cool the entire exhaust air stream sufficiently. Particularly when a bioreactor is used as a disposable reactor with a condenser, it is difficult to achieve a compact form of construction. What proves to be especially critical in this case is the possible blocking of the hydrophobic sterile filter if the vessel of the bioreactor is designed as a flexible plastic bag, the internal pressure of which should not exceed specific limit values so that, if necessary, gassing and therefore the fermentation process have to be discontinued.
Furthermore, U.S. Pat. No. 6,133,021 A discloses a bioreactor, the gas dissipation duct of which is connected to a condenser. This condenser, too, has the disadvantages described above.
Furthermore, DD 260 837 A3 discloses a bioreactor with a vessel which has a gas dissipation duct for gas discharge. The orifice of the gas dissipation duct is connected to an exhaust air filter, a condenser being arranged between the vessel and the exhaust air filter.
This known bioreactor, too, has the abovementioned disadvantages.
EP 1 167 905 A2 discloses an apparatus for removal of volatile components from a gas stream, using a cryogenic process. In order to remove the volatile components from a process gas stream, the gas stream is cooled in a condenser in order to convert the volatile components into liquid and ice. The process gas, which is freed from the volatile components and may still contain ice particles of volatile components, passes through a filter which is arranged downstream of the condenser, in order to remove the ice particles which have a size of more than 50 μm.
This technical application, because of its refrigeration process, is not suitable for or cannot be transferred to bioreactors. The vortex, used in EP 1 167 905 A2, of liquid cryogen for cooling, on the one hand, is unsuitable for bioreactors and, on the other hand, is used in order to generate relatively large ice crystals.
GB 449 621 A discloses an apparatus for the recovery of phthalic anhydride (PSA) from vapors, in which the vapors are routed as a turbulent stream through a tubular condenser. A person skilled in the art is not given any suggestion for the development of bioreactors.
U.S. Pat. No. 3,063,259 A discloses an apparatus for the filtration and dehydration of gases. In the condenser known from U.S. Pat. No. 3,063,259 A, the process gas is conducted spirally around a spirally designed cooling wall. There is no question here of a turbulent flow in the gas dissipation duct. Not even this gives a person skilled in the art any suggestion for the development of bioreactors.
WO 2006/020177 A1 discloses a photobioreactor for photosynthetic organisms, such as algae. WO 2006/020177 A1 teaches that, in specific embodiments, a filter, such as, for example, a hydrophobic filter with a main pore diameter smaller than the mean diameter of the algae, can be used in order to prevent the escape of algae from the gas outlet of the bioreactor. Algae filters of this type are not sterile filters.
The object of the present invention, therefore, is to improve the known bioreactors and their condensers such that, while having a compact form of construction, they can be produced from plastic, in particular for disposable use.